Disposable face mask with enhanced fluid barrier

ABSTRACT

A disposable face mask that includes a filter body capable of filtering liquids and/or particles of a size appropriate for the mask&#39;s intended purposes, while providing excellent breathability and comfort to the wearer for extended periods of time. The filter body is formed from multiple layers of filtration material having various configurations. Such masks may be secured by one or more knitted headbands to the head of a wearer. Various gasket-type sealing materials such as plastic film or other materials such as hydrogel may be used to enhance the fluid barrier formed between the periphery of the mask and the wearer&#39;s face.

RELATED APPLICATIONS

"This application is a Continuation-in-Part application of pending U.S.patent application Ser. No. 08/168,090 filed Dec. 15, 1993, entitledDisposable Face Mask with Face Shield, of same assignee, now abandonedin favor of U.S. patent application Ser. No. 08/491,137 filed Jul. 17,1995, and of U.S. patent application Ser. No. 08/278,930 filed Jul. 20,1994, entitled Face Mask with Enhanced Seal and Method, of sameassignee, now U.S. Pat. No. 5,553,608. This application is related toU.S. patent application Ser. No. 07/991,154 filed Dec. 16, 1992,entitled Disposable Face Mask, of same assignee, now U.S. Pat. No.5,322,061."

TECHNICAL FIELD OF THE INVENTION

This invention relates generally to face masks capable of preventing thepassage of airborne aerosols, particulate matter and/or liquids. Moreparticularly, and not by way of limitation, this invention relates todisposable face masks having an enhanced fluid barrier between theperiphery of the mask and a wearer's face. Also, this invention allowsusing various materials to enhance the filtration capabilities of theresulting mask for the specific operating environment while maintaininggood breathability.

BACKGROUND OF THE INVENTION

Disposable face masks have been manufactured for many years. In themedical field, many of these early masks were used in preventingcontamination of a patient by the breath of health care personnel. Inrecent years with increased concern for infection of health carepersonnel with airborne pathogens, such as the hepatitis B virus, it hasbecome necessary to not only prevent contamination of patients due toexhalation from health care personnel, but also to prevent infection ofhealth care personnel due to inhalation of airborne infection particles.It has become even more important in view of the advent of humanimmunodeficiency virus (HIV) and the recent increase in infectioustuberculosis associated with many HIV patients.

The rapid increase of infectious diseases, particularly AIDS, has madethe use of such protective equipment increasingly important. The Centerfor Disease Control in Atlanta, Ga., has found that the AIDS virus (HIV)can be passed by contact with body fluids. Contact of AIDS contaminatedbody fluids with another person's source of body fluids, e.g., eyes,nose, mouth, etc., can pass the disease. Therefore, it is necessary toprevent a patient's body fluids from contacting the face of health carepersonnel.

Aerosols having airborne liquid and solid particles are generated notonly by the exhalation of infected patients, but also by certainprocedural manipulations and processes that impart energy to any liquidor microbial suspension. Surgical procedures involving use of drills andsaws are particularly prolific producers of aerosols which may containtuberculosis, HIV or other pathogens from an infected patient. Concernwith tuberculosis has been increasing since new strains of the diseaseshow strong resistances to multiple types of drug treatment.

One type of mask is illustrated in U.S. Pat. No. 2,012,505 entitledMask, issued on Aug. 27, 1935 to S. J. Goldsmith. Another type ofdisposable face mask is illustrated in U.S. Pat. No. 4,319,567 entitledDisposable Face Mask, issued on Mar. 16, 1982 to M. Magidson. This maskis molded and has been especially configured in an effort to avoidleakage of fluid flow past the edges of the mask. Obviously, leakagecannot be tolerated when attempting to control liquids and/or aerosols.U.S. Pat. No. 4,606,341 entitled Noncollapsible Surgical Face Mask,issued Aug. 19, 1986 to Vance M. Hubbard and Welton K. Brunson shows aconventional rectangular face mask having a trapezoidal pleat. For someoperating conditions, rectangularly shaped masks, including the maskshown in Patent '341, may have less than an optimal fit to prevent thepassage of liquids and aerosols between the periphery of the masks and awearer's face.

Recent developments in surgical face mask have resulted in resistance toliquid penetration from the exterior of such masks. U.S. Pat. No.4,920,960 entitled Body Fluids Barrier Mask, issued on May 1, 1990 toHubbard, et al., is exemplary of improvements in such masks. U.S. Pat.No. 5,020,533 entitled Face Mask with Liquid and Glare Resistant Visor,issued on Jun. 4, 1991 to Hubbard, et al., is an example ofincorporating a visor to protect the face of a wearer from liquidsduring medical procedures.

SUMMARY OF THE INVENTION

In accordance with the present invention, a disposable face mask isprovided to substantially reduce or eliminate the shortcomingspreviously associated with disposable face masks. A disposable face maskincorporating the present invention provides an effective fluid barrieror seal with the face of a wearer, higher filtration capability withrespect to aerosols, a sufficiently low pressure drop through the maskfor comfortable breathing, and protection from liquid splashes or liquidsprays. For some applications the disposable face mask may include oneor more layers of selected materials such as expandedpolytetrafluoroethylene to enhance the filtration capability of theresulting mask.

In one aspect, this invention provides a disposable face mask comprisinga filter body for covering the nose and mouth of a wearer. The body hastop and bottom edges with the top edge arranged to extend across thebridge of the nose of the wearer and the bottom edge arranged to extendunder the wearer's chin. A layer of gasket-type sealing material ispreferably secured adjacent to the top edge and the bottom edge. A firstsecuring member may be attached to the body adjacent each end of the topedge and disposed generally about the back of the head of the wearer inan approximate linear continuation of the top edge urging the top edgeinto tight engagement with the wearer's face to prevent fluid flowbetween the top edge and the wearer's face. A second securing member maybe attached to the body adjacent to each end of the bottom edge anddisposed generally over the top of the wearer's head in an approximatelinear continuation of the bottom edge urging the bottom edge into tightengagement with the wearer's face to prevent fluid flow between thebottom edge and the wearer's face. The resulting mask provides anenhanced fluid barrier around the periphery of the mask to prevent thebypass of both liquids and aerosols between the edges of the mask andthe wearer's face.

In another aspect, the present invention provides a surgical styledisposable face mask which inhibits the passage of fluids between theperiphery of the mask and the wearer's face while providing enhancedcomfort to the wearer. The present invention may be used with standardpleated style face masks or off-the-face style masks by attaching alayer of gasket-type sealing material adjacent to top and bottom edgesof the respective mask. For some applications, a single pair of ties maybe used to secure a mask incorporating the present invention with thehead and face of the wearer. For other applications, a maskincorporating the present invention may be secured to the head and faceof the wearer with a pair of ear loops, four surgical tie strips or acontinuous loop of resilient material. Fluid impervious flaps may beincluded to extend the coverage area of the face mask and improve thefluid seal in cooperation with the gasket-type sealing material betweenthe periphery of the mask and the face of the wearer.

A further aspect of the present invention includes combining gasket-typesealing material disposed on the periphery of the respective face maskwith securing means formed from resilient material to provide comfort tothe wearer while maintaining a tight peripheral seal for long periods oftime. The securing means may be formed from various types of material asdesired. For some applications, the gasket-type sealing material may beplaced on the interior surface of a generally rectangular surgical styleface mask along the top and bottom edges and along each side of the facemask.

The present invention provides significant technical advantages byforming a barrier which prevents the passage of liquids and aerosolsbetween the periphery of the mask and the wearer's face. The resultingface mask blocks liquid spray and aerosols from passing through theexterior of the mask or around the edges of the face mask and contactingportions of the wearer's face. The mask provides substantially increasedflow area for the passage of air through the mask during normalbreathing by the wearer while at the same time allowing the use offiltration media having higher resistance to the passage of liquids andaerosols through the mask. The present invention allows optimizing thefiltration capability for resistance to the passage of aerosols whileminimizing the restriction to normal breathing caused by wearing themask and allows for a substantially enhanced fit between the peripheryof the mask and the contours of a wearer's face.

Further technical advantages of the present invention include the use ofa filter media formed from expanded polytetrafluoroethylene (PTFE)membrane with one or more layers of bicomponent polyethylene orpolypropylene disposed on opposite sides of the filter media.Gasket-type seals may be formed in accordance with the teachings of thepresent invention to provide an effective fluid barrier between theperiphery of both pleated and non-pleated type face masks and thewearer's face. The gasket-type seals may be formed by thin layers ofplastic film materials such as polyethylene and polypropylene. For otherapplications, various types of hydrogel may be disposed on the peripheryof the associated face mask in combination with or as a replacement forthe gasket-type sealing material.

A further aspect of the present invention includes placing gasket-typesealing material on the interior surface of a face mask to form a fluidbarrier with the wearer's face. By forming a gasket-type seal inaccordance with the teachings of the present invention, normal movementof the face mask associated with breathing and talking by the wearerwill not compromise the fluid barrier formed between the gasket-typesealing material and the wearer's face.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present invention andadvantages thereof, reference is now made to the following descriptiontaken in conjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view of a disposable face mask incorporating anembodiment of the present invention illustrated on the head of a wearer;

FIG. 2 is the plan view of the mask shown in FIG. 1;

FIG. 3a is a drawing in section and in elevation with portions brokenaway of the mask shown in FIG. 1 taken generally along lines 3a--3a ofFIG. 2;

FIG. 3b is a drawing in section and in elevation with portions brokenaway showing a disposable face mask incorporating an alternativeembodiment of the present invention;

FIG. 3c is an enlarged sectional view with portions broken away showingan alternative embodiment of the mask of FIG. 1 with four layers ofmaterial including at least one liquid impervious layer;

FIG. 3d is an enlarged sectional view with portions broken away showinganother alternative embodiment of the mask of FIG. 1 with three layersof material including at least one layer of expanded PTFE filter media;

FIG. 3e is an enlarged drawing with portions broken away showing afurther alternative embodiment with hydrogel placed on gasket-typesealing material attached to the interior periphery of the mask of FIG.1;

FIG. 4 is a prospective view of a disposable face mask incorporatingstill another embodiment of the present invention illustrated on thehead of a wearer;

FIG. 5 is a front plan view of the mask shown in FIG. 4;

FIG. 6 is a back plan view of the mask shown in FIG. 4; and

FIG. 7 is a back plan view of a face mask incorporating a furtherembodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The preferred embodiments of the present invention and its advantagesare best understood by referring to FIGS. 1-7 of the drawings, likenumerals being used for like and corresponding parts of the variousdrawings.

Disposable face masks 10, 110, 210 and 310 incorporating variousfeatures of the present invention may be used to retard the flow ofbacteria, liquids, particulate matter and aerosols from the exterior ofthe respective mask to the nose and mouth of a wearer. For purposes ofthis application aerosols are defined as insoluble liquids orparticulate matter frequently associated with microbial solutions. Theterm "fluid" is used within this application to include any gas, liquid,or mixture of gas and liquid. Various types of particulate matter andaerosols may be entrained with such fluids.

The present invention forms a gasket-type seal to provide an enhancedfluid barrier between the periphery of a disposable face mask and theface of a wearer. For purposes of this application, the term"gasket-type seal" means a fluid barrier or pressure tight seal formedby placing a deformable material between two relatively stationaryobjects. Such gasket-type seals are sometimes referred to as "staticseals." A wide variety of gasket-type sealing materials including thinplastic films and/or hydrogels, may be satisfactorily used to form agasket-type seal between the periphery of a face mask and the face of awearer in accordance with the teachings of the present invention. Othertypes of deformable material such as open cell and closed cell foams mayalso be used to form the desired gasket-type seal.

The present invention allows optimizing the filtration capability of adisposable face mask to resist the passage of liquids, particulatematter and/or aerosols while at the same time minimizing resistance tonormal breathing by a wearer and providing a comfortable fit forextended periods of wear. The present invention allows using one or moremultiple layers of filter media which may be specifically designed toblock the passage of aerosols in addition to liquids.

Mask 10 incorporating some of the teachings of the present invention inshown in FIG. 1 as being positioned on the face of wearer 12 who isillustrated in ghost lines. Mask 10 includes filter body 14 which issecured to wearer 12 by resilient securing members or headbands 16 and18. Filter body 14 comprises an upper portion 20 and a lower portion 22which have a generally trapezoidal configuration. Upper and lowerportions 20 and 22 preferably have matching exterior dimensions andshape. Upper and lower portions 20 and 22 may be bonded together by heatand/or ultrasonic sealing along three sides of filter body 14. Bondingin this manner adds important structural integrity to mask 10.

The fourth side of filter body 14 is open and includes a top edge 24with an elongated malleable member 26 (see FIGS. 2 and 3a). Malleablemember 26 is provided so that top edge 24 of mask 10 can be configuredto closely fit the contours of the nose and cheeks of wearer 12.Malleable member 26 is preferably constructed from an aluminum stripwith a rectangular cross-section, but may also be a moldable ormalleable steel or plastic member.

Top edge 24 of upper portion 20 and bottom edge 38 of lower portion 22cooperate with each other to define the periphery of mask 10 whichcontacts the face of wearer 12. The present invention allows optimizingthe barrier formed between the periphery of mask 10 and the face ofwearer 12 and the filtration capability of mask 10 to resist the passageof liquids, particulate matter and aerosols through filtration media 34while minimizing resistance to normal breathing of wearer 12 resultingfrom the use of mask 10. The present invention also allows includingmultiple layers of filter media within filter body 14 including layer 44of liquid impervious material.

As shown in FIGS. 1 and 3a, mask 10 has the general shape of a cup orcone when placed on the face of wearer 12. The present invention allowsmask 10 to provide "off-the-face" benefits of a molded-cone style maskwhile still being easy to package, store and ship. "Off-the-face" stylemasks provide a larger breathing chamber as compared to soft, pleatedmasks which contact a substantial portion of the wearer's face.Therefore, "off-the-face" style masks generally permit cooler and easierbreathing.

The present invention allows optimizing the volume of air containedwithin filter body 14. If the volume is too large, excessive amounts ofexhaled air may be retained within filter body 14 at normal breathingrates. By properly selecting the size of filter body 14, excessiveheating of the air within filter body 14 is minimized and dizziness fromprolonged periods of rebreathing exhaled air is also minimized.

The approximate optimum dimensions for mask 10 as shown in FIG. 2include 101/4 inches for the major length, dimension A, of thetrapezoidal shape of filter body 14. The length of the opening in filterbody 14 defined in part by top edge 24 and bottom edge 38, dimension B,is 91/4 inches due to approximately 1/2 inches of seal at each junctionbetween upper portion 20 and lower portion 22. The minor length of theparallel portion of trapezoid shaped filter body 14, dimension D, isapproximately 35/16 inches. The opening of filter body 14 defined inpart by dimensions A and B is generally parallel with minor length,dimension D. Dimensions A and B may be varied by ±3/4 inches. The widthof the trapezoid shape of filter body 14, dimension C, is 31/2 inches.Dimensions C and D may be varied by ±1/4 inches. The bonded borderdefining the three closed sides of mask 10, dimension E, is preferably1/4 inches in width. The inner portions of top edge 24 and bottom edge38 which contact the wearer's face, dimension F, are approximately 1/2inches in width.

Strips of gasket-type sealing material 50 and 52 are preferably disposedon the inner portion of top edge 24 and bottom edge 38 respectively.Strips 50 and 52 preferably have approximately the same length asdimension A of filter body 14 and a width of approximately 11/4 inches.For one application, strips 50 and 52 have a thickness of approximately0.0005 inches.

The above dimensions may be modified to accommodate wearers havingsmaller or larger facial features. However, the ratio between the widthof the trapezoid shape which defines mask 10, dimension C, as comparedto the minor length of the trapezoid shape, dimension D, shouldpreferably remain at approximately 1 to 1. The preferred ratio betweenthe major length of filter body 14, dimension A, and the minor length,dimension D, is approximately 3 to 1. For other applications, the ratioof dimension A to dimension D may be varied to provide the desired fitas long as dimension A is larger than dimension D and the width isapproximately equal to dimension C. Strips 50 and 52 of gasket-typesealing material allow face mask 10 to form a fluid tight barrier withwearers having a wider variety of facial features.

An important feature of the present invention is forming radius R1 ofapproximately 11/8 inches and radius R2 of approximately 3 inches in thenon-parallel or angled sides of filter body 14. Radii R1 and R2cooperate with each other and with the three bonded sides of filter body14 to prevent collapse of filter body 14 during normal breathing bywearer 12. These radii, R1 and R2, help mask 10 retain the desired,off-the-face shape during normal breathing. If the sealed border on thethree closed sides of filter body 14 is less than 1/4 inches, mask 10may tend to collapse during normal breathing. Therefore, an importantfeature of the present invention includes combining radii R1 and R2 witha sealed border of approximately 1/4 inches in width or greater toprovide the desired cone or cup shaped mask covering the nose and mouthof wearer 12 and to maintain a fluid tight barrier with wearer 12's facewithout collapsing during normal breathing.

Radius R2 curves outward from opposite sides of mask 10 and is tangentto radius R1 that curves inward towards the attachment points forheadbands 16 and 18. This arrangement serves several importantfunctions. Radii R1 and R2 cooperate with each other and strips 50 and52 to improve the facial seal performance between the periphery of mask10 and the face of wearer 12. Radii R1 and R2 allow mask 10 to open withrelatively flat surfaces near each end of top edge 24 and bottom edge 38adjacent to the attachment point for headbands 16 and 18. These flatsurfaces adjacent to the attachment points for the headbands 16 and 18gradually taper away from the opening in filter body 14. The generaltrapezoidal shape of filter body 14 in cooperation with radii R1 and R2and the other preferred dimensions and ratios cooperate to minimizecollapse of filter body 14 during normal use of mask 10.

Radii R1 and R2 cooperate with strips 50 and 52 disposed respectfully onthe inner portion of top edge 24 and bottom edge 38 to allow mask 10 tofit securely with and to form a tight facial seal with a greater numberof different face sizes. Mask 10 is particularly useful with smallerfaces which contact the tapered surfaces adjacent to the attachmentpoints for headbands 16 and 18 on the interior of mask 10 as shown inFIGS. 3a and 3b. Other types of surgical mask may also benefit fromplacing strips 50 and 52 of gasket-type sealing material between theperiphery of the respective mask and the face of the wearer.

Radii R1 and R2 assist in maintaining the integrity of mask 10 byproviding strength along the three-bonded sides of filter body 14 whenmask 10 is fully opened against the face of a wearer. These previouslydescribed design features allow for the use of lighter weight or lighterbasis material which adds breathability and comfort to mask 10. Withoutradii R1 and R2 these same lightweight materials would be prone tocollapse during inhalation. The 1/4 inches bonded seal around the threeclosed sides of filter body 14 contributes to maintaining structuralintegrity of mask 10 when secured to the face of wearer 12.

Various adhesives, ultrasonic seals and/or heat seals may be used toattach strips 50 and 52 of gasket-type sealing material respectively totop edge 24 and bottom edge 38. Ultrasonic seals (sometimes referred toas ultrasonic welds) 42 have been found to be particularly advantageousfor attaching strips 50 and 52. For some applications strips 50 and 52may be formed from polyethylene or polypropylene with a thicknessbetween 0.005 and 0.0005 inches. However, other types of thin film anddeformable materials with various thicknesses may be satisfactorily usedwith the present invention.

Blow-by associated with normal breathing of wearer 12 is substantiallyeliminated by properly selecting the dimension and location of malleablestrip 26 and gasket-type sealing material 50 with respect to top edge of24. Malleable strip 26 is preferably positioned in the center of topedge 24 and has a length in the range of fifty percent to seventypercent of the total length, dimension A, of top edge 24. For oneembodiment of the present invention, the performance of mask 10 wasenhanced by using malleable strip 26 manufactured from quarter-temperedaluminum. For this embodiment, the length of malleable strip 26 wasapproximately 54 percent of the length of top edge 24 with a thicknessof 0.021 inches and a width of 0.197 inches.

The present invention allows designing mask 10 with the optimumperiphery to fit the face of wearer 12 and the optimum dimension forstrips 50 and 52 to form an enhanced fluid barrier with the nose andface of wearer 12. The present invention allows modification to thelength of top edge 24 and bottom edge 38 while maintaining approximatelythe same surface area for normal breathing through filter media 34.

For some applications securing members 16 and 18 are preferablyconstructed from resilient polyurethane, but may be constructed fromelastic rubber or a covered stretch yarn. The covered stretch yarn mayconsist of an elastomeric material wrapped with nylon or a polyester.For other applications securing members 16 and 18 may comprise doubleknitted headbands such as circle knitted polyester/LYCRA or nylon/LYCRA.The use of resilient securing members 16 and 18 substantially improvesthe fluid barrier between the periphery of mask 10 and the face ofwearer 12.

As illustrated in FIG. 3a, upper and lower portions 20 and 22 eachinclude an outer mask layer 30 that is preferably constructed from aspun-bonded polypropylene. Outer mask layers 30 may also be constructedfrom a bi-component and/or powder bonded material such as polyethyleneor polypropylene, a cellulastic tissue, or a spun-bonded polyester.Outer mask layers 30 typically have a basis weight range of 0.5 ouncesper yard to 1.0 ounces per yard. 0.9 ounces per yard is one of thepreferred basis weights for outer layers 30.

Inner mask layers 32 are preferably composed of a bicomponentpolyethylene and polypropylene. Layers 32 may also be constructed frompolyester and/or polyethylene material or cellulastic tissue. Layers 32typically have a basis weight range of 0.4 ounce per yard to 0.75 ouncesper yard. 0.413 ounces per yard is one of the preferred basis weightsfor layers 32. One or more intermediate layers of filter media may bedisposed between outer mask layer 30 and inner mask layer 32. Selectionof the number and type of intermediate layers of filter media willdepend upon the intended use and function for mask 10.

In FIG. 3a, filter body 14 is shown with only one intermediate masklayer 34 which comprises the filter media for the associated mask 10.This layer is preferably constructed from a melt-blown polypropylene,but may be constructed from an extruded polycarbonate, a melt-blownpolyester, or a melt-blown urethane.

As shown in both FIGS. 3a and 3b, top edge 24 of masks 10 and 110 may befaced with edge binder 36 that extends across the open end of mask 10and covers malleable strip 26. In a similar manner, bottom edge 38 offace masks 10 and 110 may be encompassed in edge binder 40. Edge binders36 and 40 are preferably constructed from a spun-laced polyestermaterial. Binders 36 and 40 may also be constructed from a number ofthermally bonded bicomponent materials or from polypropylene orpolyethylene non-porous plastic films. Strips 50 and 52 are disposed onthe interior of filter body 14 adjacent respectively to edge binders 36and 40.

A plurality of sonic bonds 42 are used to attach respectively to strip50 with edge binder 36 and layers 30, 32 and 34 at top edge 24, andstrip 52 with edge binder 40 and layers 30, 32 and 34 at bottom edge 38.For face mask 10, the middle portion of strip 50 and 52 are attachedrespectively to the interior of filter body 14 with approximately 1/4inches of gasket-type sealing material extending outwardly from top edge24 and bottom edge 38. Also, approximately 1/4 inches of gasket-typesealing material 50 and 52 extends respectively from sonic bonded area42 into the interior of filter body 14.

Face mask 110 shown in FIG. 3b is similar to face mask 10 except strip150 and 152 are disposed within the respective edge binders 36 and 38such that strips 150 and 152 only extend inwardly within filter body 14.Strips 150 and 152 do not extend from top edge 24 and bottom edge 38 asshown for mask 10. FIGS. 3a and 3b thus show only two of the manyoptions available for installing strips of gasket-type sealing materialadjacent to the top edge and bottom edge of a face mask in accordancewith the teachings of the present invention.

FIG. 3c shows an alternative embodiment of the present invention inwhich filter body 14 includes two intermediate layers 34 and 44 offilter media. Layer 44 may be formed from a barrier material that is gaspermeable and permits gas (air) to pass through filter body 14 in bothdirections and is impermeable to liquid passing through mask 10 in atleast one direction. Layer 44 is preferably arranged to prevent thepassage of liquids from the exterior of filter body 14 through layer 44to the interior of filter body 14.

A more complete description of the construction and operation of suchmaterial can be found in U.S. Pat. No. 3,929,135 entitled AbsorptiveStructure Having Tapered Capillaries, issued on Dec. 30, 1975 to Hugh A.Thompson. Such materials are often constructed from a low densitypolyethylene and include small apertures which prevent liquids frompassing therethrough due to the liquid's relatively high surfacetension. U.S. Pat. Nos. '960; '533 and 5,150,703 entitled Liquid ShieldVisor for a Surgical Mask with a Bottom Notch to Reduce Glare, issued onSep. 29, 1992 to Hubbard, et al provide additional information onmaterials which may be used for layers 30, 32, 34 and 44 and face masksconstructed with such materials. These patents are incorporated byreference for all purposes within this application. Other types ofmicroporous film may be satisfactorily used with the present invention.

The use of barrier materials such as layer 44 is particularly importantwhen mask 10 is worn in an environment where the wearer may be exposedto "body fluids". These fluids such as blood, urine and saliva maycontain highly contagious germs and viruses. Contact ofAIDS-contaminated body fluids with another person's source of bodyfluids, such as the eyes, nose and mouth, may transmit the disease.Therefore, it is often preferable to include layer 44 which is resistantto the passage of liquids through filter body 14 to prevent body fluidsfrom contacting the nose and mouth of the wearer.

FIG. 3d shows another alternative embodiment of the present invention inwhich filter body 14 includes intermediate layer 134 of filter mediadisposed between layers 32. For this particular embodiment of thepresent invention the inner and outer mask layers 32 are formed from thesame type of material. However, various types of material may be usedwith intermediate mask layer 134.

For one embodiment of the present invention intermediate mask layer 134was formed from an expanded polytetrafluoroethylene (PTFE) membrane.Such materials are manufactured by W. L. Gore & Associates. A morecomplete description of the construction and operation of such materialscan be found in U.S. Pat. No. 3,953,566 entitled Process for ProducingPorous Products, issued on Apr. 27, 1976 to Robert W. Gore, and U.S.Pat. No. 4,187,390 entitled Porous Products and Process Therefor, issuedon Feb. 5, 1980 to Robert W. Gore. These patents are incorporated byreference for all purposes within this application. For someapplications and operating environments the use of filter media 134substantially enhances the performance of the resulting disposable facemask 10.

As demonstrated by the previous comments, the generally trapezoidalshape of filter body 14 including the preferred ratios for thedimensions of filter body 14, radii R1 and R2, the width of bonded sides46, 47 and 48 and strips 50 and 52 of gasket-type sealing materialallows a wide variety of materials to be used in the manufacturer of themask layers which comprise filter body 14. The present invention hassignificantly increased the types of material which may besatisfactorily used in constructing filter body 14. The presentinvention also allows more options with respect to selecting the numberof layers of material used to manufacture filter body 14.

Referring to FIG. 1, mask 10 is illustrated as being located on the faceof wearer 12. Upper portion 20 with malleable member 26 located in topedge 24 and strip 50 of gasket-type sealing material conform veryclosely to the configuration of the nose and cheeks of wearer 12. It isalso important that bottom edge 38 with strip 52 fit very closely withthe chin of wearer 12 and top edge 24 with strip 50 and the nose andcheeks of the wearer 12 fit very closely since any leaks result inbypass or blow-by of air either entering mask 10 or being dischargedfrom mask 10 when used by wearer 12. Strips 50 and 52 substantiallyreduce such leakage.

Accordingly, securing members 16 and 18 have their ends attached at thejunctures between top edge 24 and bottom edge 38 of mask 10 as shown inFIG. 3a. The arrangement is such that securing member 16 can be placedover the top of the head of wearer 12, as illustrated in FIG. 1, inalignment with bottom edge 38 of mask 10 so that a direct force isexerted along that line urging bottom edge 38 into sealing engagementwith the chin of wearer 12. Similarly, securing member 18 is positionedaround the lower base of the skull and in direct alignment with top edge24 of mask 10 and thus placing a force thereon which tends to move topedge 24 into tighter sealing engagement with the nose and cheeks ofwearer 12. As shown in FIG. 3a, the ends of securing members 16 and 18are secured at the same location between top edge 24 and bottom edge 38with no gap between the ends of securing members 16 and 18. The positionof attaching securing members 16 and 18 to filter body 14 in cooperationwith radii R1 and R2 results in the optimum pull angle to form a fluidtight barrier between strips 50 and 52 disposed on the interior of mask10 and the face of wearer 12.

In addition to having a tight peripheral seal, it is essential that mask10 have good breathability characteristics. That is, mask 10 shouldrequire a low differential in pressure to permit air to flow easilythrough filter body 14 despite the fact that layers 30, 32 and 34 areformed from material which will filter 1 micron and smaller particlesand have a very tight fit between strips 50 and 52 and the face ofwearer 12. A low differential pressure for air flow indicates goodbreathability through a mask 10 and helps to maintain the desiredgasket-type seal between the periphery of mask 10 and the face of wearer12.

For one embodiment upper portion 20 and lower portion 22 of mask 10 havea combined surface area through which air can flow of about two hundredand fifty square centimeters (250 cm²). Thus, body 14 of mask 10 has asurface area of approximately two hundred and fifty square centimeterswhich provides enhanced breathability for wearer 12. Tests were runutilizing a flow rate of thirty-two (32) liters per minute across theentire flow area. Approximately thirty masks incorporating the presentinvention were checked. The masks had a pressure differential rangingfrom 0.9 to 1.3 mm of water with a mean pressure differential across themask of about 1.25 mm of water. Such a low differential in pressureacross the mask provides excellent breathability characteristics despitethe ability of the mask to filter one micron and smaller sized particleswith essentially zero edge leakage around the periphery of mask 10.

Upper portion 20 and lower portion 22 are shown connected with eachother by heat sealing or ultrasonic bonding along sides 46, 47 and 48 toform filter body 14 having a general trapezoidal shape with an open sidedefined by top edge 24 and bottom edge 38. Securing members 16 and 18are attached to the corners of top edge 24 and bottom edge 38 at thejunction with upper portion 20 and lower portion 22 during ultrasonicbonding of sides 46, 47 and 48 of filter body 14.

In FIG. 3, layer 54 of hydrogel is shown disposed on strip 50 to furtherenhance the fluid barrier formed with the face of wearer 12. Varioustypes of hydrogel and other adhesives may be satisfactorily used withthe present invention to provide a sticky or tacky surface on strip 50to contact adjacent portions of the face of wearer 12. This feature ofthe present invention will be discussed later in more detail.

Mask 210 incorporating an alternative embodiment of the presentinvention is shown in FIGS. 4, 5 and 6. Mask 210 includes filter body228 with flaps 230 and 232 extending respectively from each side offilter body 228. As will be explained later in more detail, strips 270and 272 of gasket-type sealing material may be disposed respectivelyadjacent to top edge 244 and bottom edge 246. For some applications,filter body 228 may be fabricated in general as described in U.S. Pat.No. 4,635,628 entitled Surgical Face Mask with Improved Moisture Barrierand U.S. Pat. No. 4,969,457 entitled Body Fluids Barrier Mask. Both ofthese patents are incorporated by reference for all purposes within thisapplication.

Flaps 230 and 232 are preferably formed from fluid impervious materialfolded with a generally U-shaped cross section. Flaps 230 and 232 maysometimes be referred to as C-folds. For one application of the presentinvention, flaps 230 and 232 may be formed from polyethylene filmlaminated to a non-woven material. The non-woven material may also behydro() entangled. For other applications, the polyethylene film may belaminated to any type of material as desired. The polyethylene filmlayer may be color coded to correspond with different applications forusing the resulting face mask.

For still other applications, a breathable type film may be used to formflaps 230 and 232. For further applications, flaps 230 and 232 may beformed from resilient and/or stretchable materials. Such resilientmaterials include thermoplastic rubbers which may be extruded orinjection molded as strips or sheets of material. An example of suchthermoplastic rubbers is available under the trademark KRATON® fromShell Oil Company.

One of the benefits of the present invention is the ability to formflaps 230 and 232 from materials that have lower cost as compared to thematerial used to form filter body 228. Another benefit of the presentinvention is the ability to form strips 270 and 272 along with flaps 230and 232 from a wide variety of materials which provide an enhanced fluidseal with the face of the wearer while providing a comfortable fitduring long periods of wear. Such materials are available from varioussuppliers.

Filter body 228, flaps 230 and 232, and strips 270 and 272 arepreferably designed to prevent or retard the passage of liquids from theexterior of mask 210 to the face of wearer 212. It is extremelydifficult to construct a mask that will fit the facial configuration ofall wearers without constructing the mask specifically for eachindividual face. The use of strips 270 and 272 along with flaps 230 and232 greatly increases the different sizes and types of faces which canbe effectively protected by mask 210. Forming flaps 230 and 232 fromsuitable resilient or stretchable material further improves facial fitwith a large number of wearers.

Filter body 228 may comprise a plurality of pleats 233, 234 and 235which allow expansion of filter body 228 to cover the mouth and nose ofwearer 212. The number of pleats 233, 234 and 235 formed in filter body228 may be varied to provide the desired fit with the face of wearer212. Pleat 233 is preferably folded in a reverse direction as comparedto pleats 234 and 235. By providing reverse pleat 233, filter body 228has an increased tendency to stand away from the face of wearer 212.

For some applications filter body 228 may be formed without pleats. Forother applications, filter body 228 may be formed with non-collapsingface panels such as shown in U.S. Pat. No. 4,606,341 entitledNon-Collapsible Surgical Face Mask. U.S. Pat. No. 4,606,341 isincorporated by reference for all purposes within this application. Forstill further applications, filter body 228 may be formed from only onelayer of material or from multiple layers of material. Flaps 230 and 232allow for a wide variety of options in selecting material with thedesired breathability and fluid resistance for filter body 228.

The use of reverse pleat 233 in cooperation with pleats 234 and 235forms a larger breathing chamber as compared to other soft, pleatedstyle masks which contact a substantial portion of the wearer's face.The larger breathing chamber permits cooler and easier breathingassociated with "off-the-face" style mask such as shown in U.S. Pat. No.4,606,341. The present invention allows optimizing the volume of aircontained within filter body 228 without sacrificing comfort to thewearer or filtration efficiency.

Strips of gasket-type sealing material 270 and 272 may be formed fromthe same types of thin film materials as previously described for strips50, 52, 150 and 152. Various adhesives, ultrasonic seals and/or heatseals may be used to attach strips 270 and 272 on the interior of filterbody 228 respectively adjacent to top edge 244 and bottom edge 246. Aplurality of ultrasonic seals (sometimes referred to as ultrasonicwelds) 244a and 246a have been found to be particularly advantageous forrespectively attaching strips 270 and 272.

If the breathing chamber formed by filter body 228 is too large,excessive amounts of exhaled air may be retained within filter body 228at normal breathing rates. By properly selecting the size of filter body228 and flaps 230 and 232, excessive heating of air within filter body228 is minimized and dizziness from prolonged periods of re-breathingexhaled air is also minimized. Since the present invention results in anenhanced fluid seal or barrier formed in part by strips 270 and 272between the periphery of mask 210 and the face of wearer 212,incorporating the benefits of an "off-the-face" style face mask areimportant for extended periods of wearing mask 210.

As shown by the cutaway portion of FIG. 5, filter body 228 includes fourlayers of material with an external surface of cover stock 236 as theoutermost layer. Inner layer or internal surface 238 which contacts theface of wearer 212 may be constructed of a light weight, highly porous,softened, non-irritating, non-woven fabric, such as Dexter, Inc. productNo. 3768. Inner layer 238 is designed to prevent unwanted materials suchas facial hair, loose fibers or perspiration from contactingintermediate layers 240 and 242 which might cause a wicking effect todraw liquids through filter body 228. Inner layer 238 also provides acomfortable surface for contact with the face of wearer 212.

Intermediate layer 240 preferably comprises a barrier material that iscapable of differentiating between gases and liquids and may be, forexample, Visqueen Film Products' low density polyethylene, VisporeX-6212. Non-wetting materials, such as used to form barrier material240, have small apertures which prevent liquids with a relatively highsurface tension from passing therethrough yet will allow gases with alow surface tension to pass therethrough. It is preferable to have theapertures as large as possible to allow easy breathing, and yet smallenough to retard or prevent the flow of liquids. Intermediate layer 240is designed to freely pass gases in either direction, while restrictingthe passage of liquids in at least on direction. Filter body 228 isconstructed with barrier material 240 positioned to restrict liquidpassage from the exterior of mask 210. Further description of theconstruction and operation of such barrier material may be found in U.S.Pat. No. 3,929,135 issued Dec. 230, 1975, to Thompson, assigned toProctor and Gamble Co., and is incorporated by reference for allpurposes.

The next intermediate layer is preferably filtration media 242, whichmay be, for example, melt blown polypropylene or polyester. Filtrationmedia 242 is provided to inhibit the passage of airborne bacteria ineither direction which will prevent passage of germs to and from wearer212. Outermost layer 236 provides the external surface for filter body228, which may be treated, for example, by spraying with a liquidrepellant to render the external surface material resistant to liquids.

Outer layer 236 and filtration media layer 242 serve as an aid tobarrier material 240 by slowing down any liquid that may be splashed,sprayed or thrown at mask 210. By requiring the liquid to pass throughlayers 236 and 242 prior to reaching barrier material 240, the liquidwill have less pressure and barrier material 240 will be better able toprevent passage of the liquid. Outer layer 236 may be formed fromnon-woven material such as cellulose fiber.

Filter body 228 may be formed by bonding layers 236, 238, 240, and 242with each other in a generally rectangular configuration. Such bondingis preferably provided along top edge 244, bottom edge 246 and lateraledges 250 and 252, respectively. The corresponding bonded areas 244a,252a, 246a, and 250a may be formed by sewing, glue, heat sealing,welding, ultrasonic bonding and/or any other suitable bonding procedure.

Flaps 230 and 232 are preferably integrally attached to filter body 228as part of the respective bonded areas 250a and 252a. Flaps 230 and 232are preferably formed from fluid impervious material such as a plasticmembrane and folded with a U-shaped configuration to form an opening toreceive tie strips 216 and 218 therein. Bonded areas 220 and 222 arepreferably used to secure the approximate mid-point of tie strips 216and 218 with corresponding mid-points of flaps 230 and 232.

Top edge 244 of filter body 228 preferably includes an elongatedmalleable member 226 provided so that top edge 244 of filter body 228can be configured to closely fit the contours of the nose and cheeks ofwearer 212. Malleable member 248 is preferably constructed from analuminum strip with a rectangular cross section, but may also be amolded or malleable steel or plastic member. Top edge 244, bottom edge246 and flaps 230 and 232 cooperate with each other to define theperiphery of mask 210 which contacts the face of wearer 212. Strips 270and 272 along with flaps 230 and 232 substantially increase the area ofcontact with the face of wearer 212 as compared to a face mask havingonly tope edge 242, bottom edge 246 and lateral sides 250 and 252 incontact the face of wearer 212.

Typically surgical style pleated face masks have a generally rectangularor square configuration of approximately 7×7 inches prior to pleating.The length and width dimensions of a typical face mask may vary by ±1/2inches resulting in a face mask which is often rectangular inconfiguration as compared to a square. For some applications, thepresent invention allows reducing the length of top edge 244 from 7inches to as short as 41/2 to 5 inches. Alternatively, the presentinvention allows increasing the length of top edge 244 as desired. Also,the distance from top edge 244 to bottom edge 246 when mask 210 has beenplaced over the face of wearer 212 may be reduced from 7 to 51/2 to 6inches. Therefore, flaps 230 and 232, along with other features of thepresent invention allow reducing the total area of the filter mediaassociated with mask 210 from approximately 49 square inches to 25square inches to 30 square inches while maintaining approximately thesame effective area. This reduction in area results in a substantialsavings in the cost of materials used to fabricate mask 210 while, atthe same time, maintaining good breathability, high efficiencyfiltration, and providing an improved seal between the periphery of mask210 and the face of wearer 212 by incorporating strips 270 and 272.

The arrangement of surgical ties 216 and 218 is such that portions 216aand 218a extending from top edge 244 may be placed over the top of thehead of wearer 212. Portions 216b and 218b extending from bottom edge246 may be positioned around the lower base of the head of wearer 212 asillustrated in FIG. 4. Positioning tie strips 216 and 218 in this mannerresults in compressing or gathering the respective flaps 230 and 232 toform a flat, flange type fluid barrier with the face of wearer 212.Also, securing surgical ties 216 and 218 in this manner urges strip 270and 272 of gasket-type sealing material disposed respectively along topedge 244 and bottom edge 246 into fluid sealing engagement with thecontours of the face of wearer 212. Surgical tie strips 216a, 218a, 216band 218b may be positioned on the head of wearer 212 to provide theoptimum full angle and the optimum amount of force to form the desiredfluid barrier between the periphery of mask 210 and the face of wearer212.

Top edge 244 with malleable member 248 conforms very closely to theconfiguration of the nose and cheeks of wearer 212. It is important thatbottom edge 246 and the chin of wearer 212 and top edge 244 and the noseand cheeks of wearer 212 fit very closely since any leaks result inbypass or blow-by of fluids either entering mask 210 or being dischargedfrom mask 210 during use by wearer 212.

For some applications, filter body 228 may include outer mask layer 236that is preferably constructed from a spun-bonded polypropylene. Outermask layer 236 may also be constructed from a bi-component and/or powderbonded material such as polyethylene or polypropylene, a cellulastictissue, or a spun-bonded polyester. Outer mask layer 236 will typicallyhave a basis weight range of 0.5 ounces per yard of 1.0 ounces per yard.0.7 ounces per yard is one of the preferred basis weights for outerlayers 236.

Inner mask layer 238 may alternatively comprise bicomponent polyethyleneand polypropylene or bicomponent polyethylene and polyester. Layer 238may also be constructed from polyester and/or polyethylene material orcellulastic tissue. Layer 238 will typically have a basis weight rangeof 0.4 ounce per yard to 0.75 ounces per yard. 0.413 ounces per yard isone of the preferred basis weights for layer 238. One or moreintermediate layers of filter media may be disposed between outer masklayer 236 and inner mask layer 238. Selection of the number and type ofintermediate layers of filter media will depend upon the intended useand function for mask 210. In FIG. 5, filter body 228 is shown with onlytwo intermediate mask layers 240 and 242 which comprises the filtermedia for mask 210. These layers may be constructed from melt-blownpolypropylene, extruded polycarbonate, melt-blown polyester, ormelt-blown urethane.

Various types of material may be used for intermediate mask layers 240and 242. For example, intermediate mask layer 240 may be formed from anexpanded polytetrafluoroethylene (PTFE) membrane. Such materials aremanufactured by W. L. Gore & Associates. A more complete description ofthe construction and operation of such materials can be found in U.S.Pat. No. 3,953,566 entitled Process for Producing Porous Products,issued on Apr. 27, 1976 to Robert W. Gore, and U.S. Pat. No. 4,187,390entitled Porous Products for Process Therefor, issued on Feb. 5, 1980 toRichard W. Gore.

The present invention allows designing mask 210 with the optimumperiphery to fit the face of wearer 212, the optimum dimensions formalleable strip 248 to form an enhanced fluid barrier with the nose andface of wearer 212. The present invention allows modification to thelength of top edge 244 and bottom edge 246 while maintaining therequired surface area for efficient filtration and normal breathingthrough filter media 240.

The use of barrier materials which block the passage of liquids isparticularly important when mask 212 is worn in an environment wherewearer 212 may be exposed to "body fluids." These fluids such as blood,urine and saliva may contain highly contagious germs and viruses.Contact of AIDS-contaminated body fluids with another person's source ofbody fluids, such as the eyes, nose and mouth, may transmit the disease.Therefore, it is often preferable to include layer 240 and/or 242 whichare resistant to the passage of liquids through filter body 228 toprevent body fluids from contacting the nose and mouth of wearer 212.

Various types of securing means may be used to attach a maskincorporating the present invention to the face of a wearer. Tie strips216 and 218 shown in FIGS. 4-6 represent one of these alternativesecuring means. Also, elastic ear loops, such as shown in U.S. Pat. No.4,802,473 entitled Face Mask with Ear Loops, may be satisfactorily usedwith the present invention. U.S. Pat. No. 4,802,473 is incorporated byreference for all purposes within this application. Tie strips 216 and218 may be replaced by a continuous loop of resilient material which isdisposed within but not bonded to flaps 230 and 232.

Surgical ties 216 and 218 may be formed from various types of material.For one application of the present invention surgical ties 216 and 218are preferably formed from thermally bonded polypropylene having a basisweight of 1.5 to 1.65 ounces per square yard. This particular type ofmaterial can be ultrasonically welded, stitched or heat and pressurebonded in various patterns to provide a resilient securing means for usein attaching mask 210 to the face of wearer 212.

As shown in FIGS. 5 and 6, a single sonic stitch 224 is provided alongthe length of each surgical tie 216 and 218 to provide the desiredlongitudinal stretch and recovery capability. Single sonic stitchpattern 224 allows most of the material used to form surgical ties 216and 218 to be open and free from the associated bonded area. Stitchpattern 224 allows surgical ties 216 and 218 to retain their naturallyresilient characteristics.

By providing resilient surgical ties 216 and 218, the periphery of facemask 210 will maintain a tight fluid barrier with the face of wearer 212over a relatively long period of time. Talking and other activities bywearer 212 will not compromise the integrity of the resulting fluidbarrier. Laminated strips of material may also be used to form ties 216and 218.

Mask 310 incorporating still another embodiment of the present inventionis shown in FIG. 7. Except for the addition of strips 274 and 276 ofgasket-type sealing material, mask 310 is essentially the same aspreviously described mask 210. Strips 274 and 276 may be formed from thesame gasket-type sealing material as strips 270 and 272. Strip 276extends laterally along side 252 of filter body 228 between top edge 244and bottom edge 246. In a similar manner, strip 276 extends laterallybetween top edge 244 and bottom edge 246 along side 250 of filter body228. Only a portion of each strip 270, 272, 274 and 276 is preferablybonded with the interior of face mask 310 to provide flexibility betweenstrips 270, 272, 274 and 276 and filter body 228. Strips 270, 272, 274and 276 cooperate with each other to allow limited movement of filterbody 224 during normal talking and/or breathing of wearer 212 withoutcompromising the fluid barrier formed between the periphery of mask 310and the face of wearer 212.

For some applications it may be desirable to apply suitablehydrogel-type materials and/or other biocompatible adhesive compounds tostrips 50 and 52 for mask 10, strips 150 and 152 for mask 110 strips 270and 272 for mask 210 and strips 270, 272, 274, and 276 for mask 310. Forother applications strips 50, 52, 150, 152, 270, 272, and 274 and/or 276may be eliminated from their respective face masks 10, 110, 210, and 310and replaced by applying a layer of hydrogel or adhesive to the topedge, the bottom edge, and/or lateral rider of the respective face mask.For example, it may be desirable to apply hydrogel to lateral sides 250and 252 on the interior surface of mask 210.

Examples of hydrogel type materials and compounds satisfactory for usewith the present invention are shown in U.S. Pat. No. 5,306,504 entitledSkin Adhesive Hydrogel, Its Preparation and Uses; U.S. Pat. No.5,254,338 entitled External Application Base or Auxiliary Agent andExternal Application Composition for Human Being or Animal Containingthe Same; and U.S. Pat. No. 5,183,664 entitled Thin Film at ECDressings, Preparation and Use. These three patents are representativeof only a few of the many types of hydrogel materials and compoundswhich may be satisfactorily used with the present invention.

In addition to the previously discussed materials, face masks 10, 110,210 and 310 may be manufactured using a wide variety of non-wovenmaterials and/or microporous films. The teachings of the presentinvention allow incorporating new, state of the art materials into facemasks 10, 110, 210 and 310.

Although the present invention has been described in detail with respectto alternative embodiments, various changes and modifications may besuggested to one skilled in the art, and it should be understood thatvarious changes, substitutions, and alterations can be made heretowithout departing from the spirit and scope of the invention as definedby the appended claims.

What is claimed is:
 1. A disposable face mask comprising:a filter bodyhaving an opening sized to cover the nose and mouth of a wearer, thebody having top and bottom edges with the top edge arranged to extendacross the nose of the wearer and the bottom edge arranged to extendunder the chin of the wearer; the top edge having ends opposite fromeach other and the bottom edge having ends opposite from each other;first securing means attached to the filter body adjacent to each end ofthe top edge and arranged to extend generally about the back of the headof the wearer in an approximate linear continuation from the top edge,the first securing means for urging the top edge into tight engagementwith the wearer to prevent fluid flow between the top edge and thewearer; second securing means attached to the filter body adjacent toeach end of the bottom edge and arranged to extend generally over thetop of the head of the wearer in an approximate linear continuation fromthe bottom edge, the second securing means for urging the bottom edgeinto tight engagement with the wearer to prevent fluid flow between thebottom edge and the wearer; a first strip of gasket-type sealingmaterial disposed within the filter body adjacent to the opening andextending along the top edge; the first securing means and the secondsecuring means each having a respective first end and a second end withthe first end of the first securing means and the first end of thesecond securing means disposed adjacent to each other and the second endof the first securing means and the second end of the second securingmeans disposed adjacent to each other; a second strip of gasket-typesealing material disposed within the filter body adjacent to the openingand extending along the bottom edge; and the first sealing strip and thesecond sealing strip cooperating with each other to form a fluid barrierbetween the opening of the filter body and the face of the wearer. 2.The mask of claim 1 wherein the filter body further comprises:an upperportion of generally trapezoidal configuration having a longer sideforming the top edge; a lower portion of generally trapezoidalconfiguration having a longer side forming the bottom edge; and theupper and lower portions of the filter body being joined along allremaining sides extending from the opening.
 3. The mask of claim 1further comprising the first strip of gasket-type sealing material andthe second strip of gasket-type sealing material formed from a thin filmlayer of plastic type material and bonded respectively with the top edgeand the bottom edge of the opening in the filter body.
 4. The mask ofclaim 1 further comprising:a portion of the first strip of gasket-typesealing material extending from the opening of the filter body; and aportion of the second strip of gasket-type sealing material extendingfrom the opening of the filter body.
 5. The mask of claim 1 wherein thefilter body further comprises an intermediate layer of material which isgas permeable in both directions through the filter body and liquidimpermeable in the direction from outside the filter body to inside thefilter body.
 6. The mask of claim 1 wherein the filter body furthercomprises an intermediate layer of filter media formed from expandedpolytetrafluoroethylene (PTFE).
 7. The mask of claim 6 wherein thefilter body further comprises a first layer of bicomponent materialdisposed on one side of the intermediate layer of expandedpolytetrafluoroethylene and a second layer of the same bicomponentmaterial disposed on the opposite side of the layer of expandedpolytetrafluoroethylene.
 8. A disposable face mask comprising:a filterbody sized to fit over the mouth and nose of a wearer, the filter bodyhaving top and bottom edges with the top edge arranged to extend acrossthe nose and cheeks of the wearer and the bottom edge arranged to extendunder the chin of the wearer; the filter body having a pair of lateraledges extending between the top edge and the bottom edge; a first stripof sealing material disposed on the interior of the filter body adjacentto and extending along the top edge; a second strip of sealing materialdisposed on the interior of the filter body adjacent to and extendingalong the bottom edge; a separate flap of different material from thefilter body attached to each lateral edge of the filter body andarranged to extend from the filter body; first securing means and secondsecuring means attached to the respective flaps and arranged to extendgenerally about the head of the wearer, the first and second securingmeans cooperating with the flaps for urging the first strip of sealingmaterial on the top edge and the second strip of sealing material on thebottom edge into tight engagement with the wearer to prevent undesiredfluid flow between the top edge and the bottom edge and the wearer'sface; and the flaps cooperating with their respective first securingmeans and second securing means to prevent undesired fluid flow betweenthe respective lateral edges of the filter body and the face of thewearer.
 9. The mask of claim 8 wherein the first strip of sealingmaterial and the second strip of sealing material further comprise athin layer of plastic film bonded respectively with the top edge and thebottom edge of the filter body with a portion of the first strip ofmaterial and a portion of the second strip of sealing material extendingrespectively from the top edge and the bottom edge of the filter body.10. The mask of claim 8 further comprising an elongated malleable memberlocated in the top edge for conforming the top edge to the contours ofthe wearer's nose and cheeks.
 11. The mask of claim 8 wherein the firststrip of sealing material and the second strip of sealing materialcomprises hydrogel.
 12. The mask of claim 8 wherein the filter bodycomprises a layer of filter media for restricting the flow of liquidsthrough the filter body.
 13. The mask of claim 8 wherein the filter bodyfurther comprises an intermediate layer of filter media formed fromexpanded polytetrafluoroethylene (PTFE).
 14. The mask of claim 8 whereinthe filter body further comprises a first layer of bicomponent materialdisposed on one side of the intermediate layer of expandedpolytetrafluoroethylene and a second layer of the same bicomponentmaterial disposed on the opposite side of the layer of expandedpolytetrafluoroethylene.
 15. A disposable face mask comprising:a filterbody having an opening sized to cover the nose and mouth of a wearer,the filter body having top and bottom edges with the top edge arrangedto extend across the nose and cheeks of the wearer, and the bottom edgearranged to extend under the chin of the wearer; the filter comprisingan upper portion of generally trapezoidal configuration having a longerside forming the top edge and a lower portion of generally trapezoidalconfiguration having a longer side forming the bottom edge; the longerside of the top edge and the longer side of the bottom edge havinggenerally matching dimensions and defining in part the opening of thefilter body; the body and lower portions being joined along allremaining sides; and the filter body having a shorter side opposite fromthe longer side and generally parallel with the longer side, and thelength of the longer side approximately three times the length of theshorter side.
 16. The mask of claim 15 wherein the filter body furthercomprises:the dimensions of the upper portion corresponding to thedimensions of the lower portion; and the distance from the longer sideto the shorter side approximately equal to the length of the shorterside.
 17. A disposable face mask comprising:a filter body having anopening sized to cover the nose and mouth of a wearer, the filter bodyhaving top and bottom edges with the top edge arranged to extend acrossthe nose and cheeks of the wearer, and the bottom edge arranged toextend under the chin of the wearer; the filter body comprising an upperportion of generally trapezoidal configuration having a longer sideforming the top edge and a lower portion of generally trapezoidalconfiguration having a longer side forming the bottom edge; the longerside of the top edge and the longer side of the bottom edge havinggenerally matching dimensions and defining in part the opening of thefilter body; the upper and lower portions of the filter body beingjoined along all remaining sides; the filter body having a shorter sideopposite from the longer side and generally parallel with the longerside and the length of the longer side approximately three times thelength of the shorter side; a first strip of sealing material disposedwithin the filter body adjacent to the opening and extending along thetop edge; a second strip of sealing material disposed within the filterbody adjacent to the opening and extending along the bottom edge; andthe first sealing strip and the second sealing strip cooperating witheach other to form a fluid barrier between the opening of the filterbody and the face of the wearer.
 18. The mask of claim 17 wherein thefilter body further comprises:the dimensions of the upper portioncorresponding to the dimensions of the lower portion; and the distancefrom the longer side to the shorter side approximately equal to thelength of the shorter side.
 19. The mask of claim 17 wherein the filterbody further comprises an intermediate layer of material which is gaspermeable in both directions through the filter body and liquidimpermeable in the direction from outside the filter body to inside thefilter body.
 20. The mask of claim 17 wherein the first strip of sealingmaterial and the second strip of sealing material further compriseshydrogel.
 21. The mask of claim 17, further comprising:the first stripof sealing material extending partially from the opening of the filterbody; and the second strip of sealing material extending partially fromthe opening of the filter body.
 22. A disposable face mask comprising:afilter body having an opening sized to cover the nose and the mouth of awearer, the body having top and bottom edges with the top edge arrangedto extend across the nose of the wearer and the bottom edge arranged toextend under the chin of the wearer; the top edge having ends oppositefrom each other and the bottom edge having ends opposite from each otherwith at least three edges of the filter body extending from the top edgeand the bottom edge; first securing means attached to the filter bodyadjacent to each end of the top edge and arranged to extend generallyabout the back of the head of the wearer in an approximate linearcontinuation of the top edge, the first securing means for urging thetop edge into tight engagement with the wearer for preventing fluid flowbetween the top edge and the wearer; second securing means attached tothe filter body adjacent to each end of the bottom edge and arranged toextend generally over the top of the wearer's head in an approximatelinear continuation of the bottom edge, the second securing means forurging the bottom edge in tight engagement with the wearer forpreventing fluid flow between the bottom edge and the wearer; the firstsecuring means and the second securing means each having a respectivefirst end and a second end with the first end of the first securingmeans and the first end of the second securing means disposed adjacentto each other and the second end of the first securing means and thesecond end of the second securing means disposed adjacent to each other;a bonded border formed along the at least three edges of the filter bodywith the bonded border forming in part at least three closed sides ofthe filter body extending from the opening; a first strip of materialdisposed within the filter body adjacent to the opening and extendingalone the top edge to form a fluid seal with the face of the wearer; anda second strip of material disposed within the filter body adjacent tothe opening and extending alone the bottom edge to form a fluid sealwith the face of the wearer.
 23. The mask of claim 22 wherein the bondedborder further comprises a width of approximately 1/4 inches.
 24. Themask of claim 22, further comprising:the first strip of sealing materialextending partially from the opening of the filter body; and the secondstrip of sealing material extending partially from the opening of thefilter body.
 25. A disposable face mask comprising:a filter body sizedto fit over the mouth and nose of a wearer, the filter body having topand bottom edges with the top edge arranged to extend across the noseand cheeks of the wearer and the bottom edge arranged to extend underthe chin of the wearer; the filter body having a pair of lateral edgesextending between the top edge and the bottom edge; a separate flapattached to each lateral edge of the filter body and arranged to extendfrom the filter body; the flaps formed from fluid impervious, resilientmaterial which is different from the material used to form the filterbody; first securing means and second securing means attached torespective flaps and arranged to extend generally about the head of thewearer, the first and second securing means cooperating with therespective flaps for urging the top edge and the bottom edge into tightengagement with the face of the wearer to prevent undesired fluid flowbetween the top edge and the bottom edge and the wearer's face; theflaps cooperating with their respective first securing means and secondsecuring means to prevent undesired fluid flow between the respectivesides of the filter body and the face of the wearer; a first strip ofmaterial disposed within the filter body adjacent to and extending alongthe top edge for forming a fluid seal with the face of the wearer; and asecond strip of material disposed within the filter body adjacent to andmending along the bottom edge for forming a fluid seal with the face ofthe wearer.
 26. The mask of claim 25, further comprising:the first stripof sealing material extending partially from the top edge of the filterbody; and the second stop of sealing material extending partially fromthe bottom edge of the filter body.
 27. The mask of claim 25 furthercomprising the first strip of sealing material and the second strip ofsealing material selected from the group consisting of thin plasticfilm, hydrogel, polyethylene and polypropylene.